sewforum.com has one digitised by vonieta, you will have to register then look in search page for diaper and there u will find it
gramma had a free set of monogram one that is for sale now
Yes Carol at www.designsandbearstoo.com has an alphabet like that
I'm sorry I don't know of one exactly like you are looking for.
1. diaper pin border, you could put your own alpha inside
2. diaper pins - scroll down, again you could put a letter next to it.
3. a diaper design you might like